Criminal law addresses the government's prosecution of individuals who have committed an act classified as a crime. Federal, state, and local governments codify crimes and prosecute criminals. A prosecuting attorney represents the people of a particular jurisdiction, and acts on behalf of the government by bringing a case against an accused.
Crimes involve the act or omission of an act in violation of a public law forbidding or commanding it. While common law crimes (crimes established though judicial decisions) do exist, most crimes are defined in statutes. For example, the U.S. Code contains a list of federal crimes. (18 U.S.C. § 1). Each state and local municipality also publishes a penal code detailing the various forms of criminal liability pertinent to its jurisdiction. The Model Penal Code (adopted by the American Law Institute, May 24, 1962) illustrates the most common types of crimes, and serves as a template for developing new forms of criminal liability.
Crimes generally fall into one of four categories: crimes against the person, property crimes, crimes against justice, and inchoate offenses. Examples of crimes against the person include: assault, battery, robbery, kidnapping, rape, murder, manslaughter, and mayhem. Property crimes involve: burglary, larceny, arson, embezzlement, false pretenses, extortion, forgery, and computer crime. Crimes against justice entail acts which impede or corrupt the judicial process, such as: obstruction of justice, bribery, and perjury. Inchoate offenses concern acts which lead to the commission of an additional crime. Thus, solicitation, attempt, conspiracy, and accessory are inchoate offenses.
In order to succeed, the prosecution must prove each element of an offense, as outlined in a statute. Most crimes contain at least two types of elements, a criminal act (actus reus) and a particular mental state (mens rea). For example, common law battery is defined as the offensive touching of another with an intent to cause harm. Here, the harmful contact is the actus reus, or criminal act, while the intent to cause harm is the mens rea or requisite mental state. The prosecution must also convince the fact finder, either the judge or the jury, that the accused is guilty beyond a reasonable doubt.
Once a person is suspected of committing a crime, he or she becomes involved in the judicial process. The government issues a complaint or an indictment against the person suspected of the crime (the defendant). In federal court, felony indictments must be brought by a grand jury. States have their own polices regarding issuing complaints.
The United States Constitution and Supreme Court cases outline the protections afforded to an accused. The Fourth Amendment of the United States Constitution regulates the procedures that the police must use when searching or arresting a defendant. Terry v. Ohio [392 U.S. 1 (1968)] explains the protections afforded by the Fourth Amendment when the police wish to detain a citizen.
The government must have probable cause to believe a person committed a crime before he or she is arrested. The Fifth and Sixth Amendments of the Constitution protect an individual from unlawful interrogation by the police. Case law, such as Miranda v. Arizona [384 U.S. 436 (1966)] also condemns unlawful questioning by the police. In addition, the Sixth Amendment guarantees the right to a jury, the right to confront witnesses, and the right to counsel. Furthermore, the Fourteenth Amendment provides the right to due process. Arizona v. Fulminante [500 U.S. 938 (1991)] illustrates the Fourteenth Amendment protections afforded to a defendant when confronted by the police.
After a judgment has been entered against a defendant, the defendant may appeal to higher courts. When a defendant has been convicted he or she must then serve his or her sentence. Punishments for criminal offenses usually entail incarceration and/or fines. Misdemeanors involve imprisonment of less than a year, while felonies require sentences of a year or more. The Eighth Amendment of the U.S. Constitution protects the defendant from cruel or excessive punishment.